Process of rolling metal



1931- M. c. CORRIGAN ET AL 1,829,339

PROCESS OF ROLLING METAL Filed July 17, 1929 gwwmtow M/chqe/ C. Ccrr/gan'Dawd t. Jenkms Patented Oct. 27, 1931 UNITED STATES PATENT OFFICE,

MICHAEL O. COBRIGAN, .OF MASSILLON, AND DAVID E. JENKINS, F CANTON,OHIO, AS- SIGN ORS, BY MESNE ASSIGNMENTS, TO REPUBLIC STEEL CORPORATION,OF YOUNGS- TOWN, OHIO, A.CORPORA.TION OF NEW JERSEY PROCESS OF ROLLING-METAL Application filed July 17, 1929. Serial No. 378,906.

This invention relates in general to the continuous rolling of iron,steel and other metals,

- and more particularly to a method of rolling metal, whereby certainpredetermined contours are given to the metal in successive passesthrough a series of pairs or stands of rolls.

It has heretofore been proposed to roll sheets by a method wherein thesheets are provided with convex upper and lower surfaces, the degree ofconvexity of these surfaces being reduced in successive passes untilthese surfaces are substantially flat or parallel with each other. Sucha method of rolling sheets has been disclosed in the reissue patent toTytus, No. 16,884.

In rolling sheets according to the method described in the aforesaidpatent, a number of factors are taken into consideration, such as thecontour of the rolls, the-composition and springiness of the rolls, thespacing of the rolls, or screw, the temperature of the rolls, and theshape, composition and temperature of the piece which is being rolled.These factors are so controlled that a piece of predetermined contourand temperature is engaged in each stand of a series of pairs of rolls,arranged to successively engage the piece and to reduce it to the andflatness.

r In starting with a piece, such for'e'xample as a sheet bar or slab,and attempting to roll it into a thin wide sheet by the aforesaidprocess, the bar would first be heated to a predetermined temperatureand then passed successively throu h each pair of rolls. If the rollsare all of the same size, and have concave working faces, the degree ofconcavity of these faces must decrease in each successive pair of rolls,in order that the convexity of the surfaces of the piece may be properlyreduced.

' If the piece is not reheated while it is being elongated, it resistsdeformationfor reduction to an increasing degree in each successive pairof rolls, withthe result that the rolls are-sprung to a greater extentthan they I would be if the piece was'maintained at an elevatedtemperature, as by heating it between passes.

desired gauge This increase in spring of the rolls, which I extremelydifficult to determine how muchshallower the rolls should be ground tocompensate for this increasing spring in successive pairs of rolls. Itis apparent therefore that the efi'iciency of the successive pairs ofrolls in reducing the piece decreases, and this decrease in efliciencybecomes more apparent as the finishing passes are approached.

These conditions may be corrected to some extent by increasing thespacing of the rolls, or screw, or by heating or cooling the rolls tocontrol the active pass. Increasing the spacing of the rollsnecessitates a larger number of stands or pairs of rolls to obtain theactive pass by heating or cooling the rolls is an uncertain anddiificult procedure.

where a piece having convexsurfaces isbeing rolled, the greater part ofMoreover,

the work .done by the rolls in each active pass is on the center of. thepiece, and in the final passes, it becomes necessary to watch theoperations very carefully .to avoid undue stresses in the center of thepiece, which have a tendency to cause buckling or riifiing of the piece.This difliculty becomes especially apparent in the rolling extremelywide sheets.

It is a primary object of our invention to provide a-method of rollingmetal, whereby a piece, such as a sheet bar orv slab, of predeterminedcontour is reduced in successive of extremely thin and passesthrougha'series of stands or pairs of rolls, and wherein the efliciency of therolls in reducing the piece is not affected by decrease in thetemperature of the piece.

Another object of the invention is to provide a method of rolling metal,whereby the work done by the rolls in each active pass is uniformlydistributed over the piece, so that undue stresses in the piece areavoided, and the flow of the metal is made more uniform, resulting inimproved grain structure and improved physical properties.

A further object of the invention is to provide a method of rollingmetal, whereby sheet or strip of uniform width, gauge and fiatness maybe produced from sheet bars, slabs and the like by a continuous process.

In accordance with the invention, ingots, after removal from the soakingpit, are reduced in a blooming mill or in a slabbing mill, and out up toprovide pieces having the crosssectional contour shown in Fig. 1, or.the cross-sectional contour shown in Fig. 6 of the accompanyingdrawings, forming a part of this specification.

As shown in Fig.1, the piece is of such contour that the upper and lowersurfaces a and b thereof are slightly concave. In actual practice, thedegree of concavity of these surfaces is such that the thickness ordepth of the piece at the center is from .025" to .125" less than thethickness or depth of the piece at the side edges thereof. If. forexample, the piece is about 30 inches wide and about 3 inches thick atthe edges. the thickness of the piece at the center .will beapproximately 2 These dimensions are'given by way of example only, andare not intended to restrict the scope of practice of the invention, theP scope of the invention being defined by the appended claims.

We may begin with a piece having the cross-sectional contour shown inFig. 6. In this case, only one of the surfaces, preferably the uppersurface a of the piece is concave, while the lower surface at issubstantially flat.

If desired, the upper and lower surfaces of the piece may be concaved indifferent degrees, and the side edges of the piece also concaved to aslight degree. as shown in Figs. 1 and 6. The corners of the piece, i.e... the junction of the upper and lower surfaces with the side edges,are preferably rounded.

In anycase, the piece is preheated to a temperature sufficiently high topermit it to be rolled down to the desiredgauge and flatness withoutreheating, but nothing 'herein is to be construed as limiting theinvention to a method wherein the piece is not to be reheated after itsinitial heating. Exigencies of rolling may make it desirable to rehea'tthe piece atom or more points during the rolling operations.

If the piece shown in Fig. 1 is to be rolled. it is passed successivelythrough'a series of pairs of rolls having convex or crowned workingfaces designed to successively reduce the degree of concavity of theupper and lower surfaces of the piece. The reductions of the concavityof the upper and lower surfacesof the piece in the successive stands orpairs of rolls is illustratedin exaggerated form in Figs. 2 to 5inclusive of the drawings. In the last stand of rolls, as

shown in Fig. 5, the active pass of the rolls is such that the pieceemerges from these rolls with the upper and lower surfaces thereofsubstantially flat or parallel with each other. lVhere all of the rollsareof approximatey the same size, it will be understood that the workingfaces of each pair of rolls are convex or crowned to a greater degreethan the faces of the succeeding pair of rolls, and in the last stand orpair 0 rolls, the facesof the rolls are crowned only sufficiently tocompensate for the spring of the rolls during the passage of 'the piecetherethrough.

If the piece shown in Fig. 6 is to be rolled, itis passed successivelythrough a series of pairs of rolls, the working faces of the upper rollof each pair beingconvexed to successively reduce the degree ofconcavity of the upper surface of the piece. The corresponding lowerroll in each pair is crowned only sufliciently to compensate for thespring of the rolls during the passage of the piece therethroughu Thelower surface of the piece is maintained as nearly flat as possible. Thereduction of the piece in successive stands of rolls is illustrated inexaggerated form in Figs. 7 to 10 inclusive of the drawings. In the laststand of rolls, the active ass is such that the piece emerges from theserolls with the upper and lower surfaces thereof substantially flat orparallel with each other. I

It will be apparent in rolling a piece by our method, that wherethe'piece is being rolled without reheating it, the increasing spring ofeach successive pair of rolls is actually utilized in the rollingoperation, for increasing the spring of the rolls is equivalenttodecreasing the convexity or crown of the rolls. In thus utilizing theincreasing spring of the rolls,=the method of rolling is made moreefficient.

It will also be apparent that the work done by'the rolls in each activepass is uniformly distributed over the piece, thereby avoidinglocalizedstresses, and resulting in a product having improved grainstructure and improved physical properties.

The term piece, as used in this specification, refers generically to asingle piece, such as an ingot, slab or sheet bar, or to other productsof rolling, such as a pack of sheets.

The term stand, as used in this specification, refers to apair of rollsthrough which the piece passes during the rolling process,

that the features and advantages of the present invention will bereadily apparent to those skilled in the art, and it will of course beunderstood that various changes may be resorted to without departingfrom the spirit or scope of theappended claims.

Claims:

1. A continuous process for reducing hot metal to sheet form insuccessive stands of rolls, which consists in passing a piece of metalfrom one stand to another successively and controllingthe active pass ofthe rolls in each stand so as to form for the next stand a piece ofslightly greater radiusof concavity curvature than the active stand.

2. A continuous process for reducing wide and thin metal to sheet formin successive stands of rolls, which consists in passing a piece ofmetal from one stand to another successively and controlling the activepass of the rolls in each stand so as to form for the next stand a pieceof slightly greater radius of concavity curvature than the active passof said next stand.

3. A continuous process for reducing hot metal to thin wide form insuccessive stands of rolls which consists in passing a piece of metalthrough one 'stand of, rolls after another successively and impressingupon the piece by the active pass of the,first and each succeeding standof rolls, a cross-sectional pass of said next shape wherein oppositesurfaces of the piece are concave, the degree of concavity decreasing ineach succeeding stand.

4. A continuous process for reducinghot metal to thin wide form insuccessive stands of rolls which consists in passing a piece of metalthrough one stand of rolls after another successivel and impressing uponthe piece by the active pass of the first and each succeeding stand ofrolls, a cross-sectional shape wherein at least one of the surfaces ofthe piece is concave, the degree of concavity decreasing in eachsucceeding stand.

5. A continuous process for reducing hot metal to sheet form insuccessive stands of rolls, which consists in passing a piece of metalfrom one stand to another successively and controlling the active passof the rolls in each stand so as to form for the next stand a piecehaving a slightly greater degree of concavity than the active pass ofsaid next stand. 0 5 v 6. A continuous process'for reducing wide andthin metal to sheet form in. successive stands of rolls, which consistsin passing a piece of metal from one stand to another successively andcontrolling the active pass of the rolls in each stand so as to form forthe next stand a piece having a slightly greater metal through one standof rolls after an other successively and impressing upon the piece bythe active pass of the first and each succeeding stand of rolls, across-sectional shape wherein the opposite surfaces of the piece areentirely concave, the degree of concavity decreasing in each succeedingstand.

8. A continuous process for reducing hot metal to thin wide form insuccessive stands of rolls which consists in passing a piece of metalthrough one stand of rolls after another successively and impressingupon the piece by the active pass of the first and each succeeding standof rolls, a cross-sectional shape wherein at least one of the surfacesof the piece is entirely concave, the degree of concavity decreasing ineach successive stand.

9. A continuous process for reducing hot metal to sheet form insuccessive passes through rolls, which consists in passing a. piece ofmetal through each pass successively and controlling each active pass soas to form for the next pass a piece of slightly greater radius of.concavity curvature than that formed by the next active pass.

10. A continuous process for reducing wide and thin metal to sheet formin successive passes through rolls, which consists in passing a piece ofmetal through each pass successively and controlling each active pass soas to-form for the next pass a piece of slightly greater radius ofconcavity curvature than that formed by the next active pass.

11. A continuous process for reducing hot metal to thin wide form insuccessive passes through rolls which consists in passing a piece ofmetal through each pass successively and impressing upon the piece byeach active pass, a cross-sectional shape wherein opposite surfaces ofthe piece are concave, the degree of concavity decreasing in eachsuccessive pass.

12. A continuous process for reducing hot metal to thin wide form insuccessive passes through rolls which consists in passing a piece ofmetal through each pass successively and impressing-upon the piece byeach active pass, a cross-sectional shape wherein at least one of thesurfaces'of the piece is concave, the de ee of concavity decreasing ineach successive pass.

13. A continuous process for reducing hot metal to sheet form insuccessive passes through rolls, which consists in passing a piece ofmetal through eac pass successively and controlling each active for thenext pass a piece having a slightly greater degree of concavity thanthat formed by the next active pass.

14. A continuous process for reducing wide and thin inetal to sheet formin successive pass so as to form passes through rolls, which consists inpassing a piece of metal through each pass successively and controllingeach active pass so as to form for the next pass a piece having a 5slightly greater degree of concavity than that formed by the next activepass. p 15. A continuous process for reducing hot metal to thin wideform in successive passes through rolls which consists in passing apiece of metal through each pass successively and impressing upon thepiece by each active pass a cross-sectional shape wherein oppositesurfaces-of the piece are entirely concave, the degree of concavitydecreasing in each successive pass.. I

v 16. A continuous process for reducing hot metal to thin wide form insuccessive passes through rolls which consists in passing a piece ofmetal through each pass successively and impressing upon the piece byeach active pass a cross sectional shape. .wherein atleast one of thesurfaces of the piece is entirely concave, the degree of concavitydecreasing in each successive pass.

17. A continuous process' of converting metal into sheet form whichcomprises repeatedly subjecting a piece of metal initially ofsubstantially rectangular transverse crosssection and having one concavesurface to roll no pressures exerted on opposite surfaces of the piece,one of-which surfaces is the said concave surface, and gradually andpro'gressively increasing the radius of curvature of the said concavesurface, until said surface is substantially flat.

18. A continuous process of converting metal into sheet form whichcomprises repeatedly subjecting a piece of metal initially ofsubstantially rectangular transverse cross- 40 section, and havingconcave opposite surfaces, to roll pressures applied to the concavesurfaces, and graduall and progressively increasing the radius 0curvature of the said concave surfaces until the said surfaces aresubstantially parallel.

In testimony whereof we aflix our signa tures.

MICHAEL C. CORRIGAN. DAVID El JENKINS.

